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From James Thomas <>
Subject Re: New ContainerPool
Date Mon, 03 Apr 2017 11:59:02 GMT
This looks fantastic - great work.
You should definitely write this up as a new blog post!

On 1 April 2017 at 14:05, Markus Thömmes <> wrote:

> Hi out there,
> Over the past couple of weeks, I started working on a new ContainerPool
> (and thus eventually a new Invoker). It started as a weekend investigation
> into how one would write the Invoker if one started on a green field and
> turned out a valuable step forward after all.
> The new ContainerPool is modeled around Akka Actors and I put an emphasis
> on the testability of the code. Before diving deeper into performance work
> on OpenWhisk we need to be able to quickly verify new models of scheduling
> and thus I abstracted the "container providing" code away from the pool
> itself. One can now easily simulate different workloads without actually
> talking to docker itself. A nice side-effect of this is, that the Container
> interface (it's literally a trait) is completely pluggable and can also be
> filled in by "insert-your-favorite-container-solution-here".
> In terms of performance I did see a significant improvement in single-user
> throughput performance but haven't yet got around to make a proper write-up
> of the experiment's setup and methodology, hence I'll not show hard numbers
> for now. We're still missing out on a common load test suite which we can
> all use to verify our changes.
> So all in all features:
> - Eliminated concurrency behavior through the actor model
> - Eliminated busy looping to get a container
> - Increased testability by drawing sharp-abstraction layers and making
> sure each component is testable separately
> - Increased "experimentability" with scheduling algorithms (they are
> encapsulated themselves)
> - Performance increases very likely due implementation of a "pause grace"
> (the container is not paused for a defined amount of time and can continue
> its work immediately if another request comes in at that time)
> - Pluggability of the container interface
> The pull-request is open at
> openwhisk/openwhisk/pull/2021. It's passing tests already. Test
> coverage is still a bit low, but Sven Lange-Last and I are working to get
> it done quite soon.
> It will be delivered in multiple smallish pull-requests, the first of
> which is open here: At
> first, the new pool is going to be behind a feature flag. Once the pool has
> battle proven, we can then flip the switch and remove old code as
> applicable.
> Feel free to have a play with it, feedback and code-reviews are very very
> welcome!
> Cheers,
> Markus

James Thomas

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